Let's say, I own example.com. It already points to a live website, which I do not under any circumstances want to accidentally prevent access to because of bumbling around with DNS settings.

I now have a new app engine project, my-project, that I want myproject.example.com to point to.

How do I do this?

The documentation that I've found on this matter is confusing and ambiguous when it comes to subdomains. Other questions / answers concerning the topic, both here and stackoverflow, are out of date and contain 404 links.

The first problem I ran into, that whilst I had verified example.com, I could not verify myproject.example.com - webmaster tools simply didn't want to validate it. And thus, this subdomain does not appear in the list of verified domains. So, as per the following image, I simply selected example.com and asked to point a subdomain to my-project:

Ambiguous DNS settings

As you can see, Google asks you to add a bunch of DNS records. But where? Do I add them to example.com or do I add them to myproject.example.com?

Since my DNS provider for example.com cannot handle adding multiple IP addresses for a single A or AAAA record, I decided I wanted to use Cloud DNS instead. So I added a new zone for myproject.example.com, and added the A and AAAA records there:

Cloud DNS zone for myproject.example.com

But, it was not possible to add the CNAME record for ghs.googlehosted.com. I don't know why, as there was no error message. The blue create button whizzes around a bit, then stops. No result.

And then we have the registrar setup, presumably where I have registered example.com, on the same Cloud DNS zone setup page:

Cloud DNS registrar setup

Which (sub)domain should these NS records go under? Are they NS records for myproject.example.com (my best guess) or should they be additional NS records for example.com?

I'm clearly doing something wrong as visiting myproject.example.com gives me a chrome ERR_NAME_NOT_RESOLVED.

  • Are you using a panel such as cpanel? – Steve Mar 1 '17 at 10:31
  • No, not using cpanel. I assume this is for DNS? – turpachull Mar 1 '17 at 10:47

To answer my own question, setting up subdomains is practically the same as setting up the naked domain. I was thrown because of the CNAME record; but this is just an alias, and if you are only using the subdomain itself, it's not needed.

Verification of the subdomain works through Google App Engine as long as the naked domain is verified first via a domain TXT record, through Google Webmaster Tools.

What I ended up doing was delegating the subdomain using Google's registrar NS records, pointing to a new DNS zone for the subdomain on Google Cloud DNS. This meant I was able to add AAAA records, and also to make use of record sets, something I was not able to do at the original DNS server UI.

  • Thanks for posting this! I've been having all kinds of trouble. I have multiple subdomains and sub subdomains. This makes sense. I hope it works! – archae0pteryx Dec 23 '19 at 15:43
  • Not sure why it didn’t give you an error message, but the underlying reason you couldn’t add a CNAME is probably that they technically aren’t supposed to exist alongside any other records at the same subdomain, since their whole point is to say “go to that nameserver for all records at this this subdomain, instead of this one”. More info: blog.cloudflare.com/… – Jacob Ford Aug 11 '20 at 15:06

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